Telephone-exchange apparatus



(No Model.) l z'sheets-sneet 1.

l J. J. CARTY. TELEPHONE BXGHANGE APPARATUS. No. 484,626. f Patented 001;. 18, 1892.

(No Model.) 2 Sheets-Sheet 2.

J. J. CARTY. TELEPHONE EXCHANGE APPARATUS.

' N0. 484,626I Patented 0013.18, 1892.

ANlilil i UNITED lSTATES PATENT OFFICE.

JOHN J. CARTY, OF NEW YORK, N. Y., ASSIGNOR TO THE WESTERN ELECTRIC COMPANY, OF CHICAGO, ILLINOIS.

TELEPHONE-EXCHANGE APPARATUS.

SPECIFICATION forming part of Letters Patent No. 484,626, dated October 18, 1892. Application tiled November 29, 1889. Serial No. 331,909. (No model.)

.To a/ZZ whom it may con/cern.-

Be it known that I, JOHN J. CARTY, a citizen of the United States, residing at New York, in the county of New York and State of New York, have invented a certain new and useful Improvement in Telephone-Exchange Apparatus, (Case No. 10,) of which the following is a full, clear, concise, and exact description, reference being had to the accompanying drawro ings, forming a part of this specication.

My invention relates to telephone-exchange Systems; and its object is to provide switching apparatus and circuits in connection with the operators telephone apparatus, so arranged that the different lines may be tested and so that the operator may bring her telephone into connection with any line or pair of lines without creating disturbances thereon or destroying the balance thereof.

My invention relates especially to multipleswitchboard systems in' which metallic circuits and grounded circuits are used conjointly upon the same switchboards.

The looping-in key which I preferably use 2 5 is of novel construction and consists in contact springs and connections so arranged that the operators telephone apparatus may be bridged across the two sides of a metallic circuit-that is to say, across the strands of the 3o pair of cords-and so that a condenser may be looped into the circuit of Aone of the cords to prevent the test-battery with which this cord is connected from causing a false test when one of the connecting-plugs is used in testing the line called for after the otherY has been inserted in the switch of a metallic-circuit line. The operators telephone is wound diiferentially, the center of the differential coils being provided with a direct ground con- 4o nection. The secondary winding of her transmitter-inductorium is also wound dierentially, the circuit on one side of these diierential windings being branched in one direction through a condenser to one strip of the loop-key and in the other direction directly to another strip of the loop-key, while from the other side of these diierential windings the circuit extends to a third strip upon the v loop-key.

5o Instead of usingadifferentially-wound telephone with the center of the coils thereof connected to ground, I have sometimes provided an ordinary single-coil telephone connected with a transmitter in the usual manner, but including in its circuit a coil of a converter, the other coil of this converter, however, being connected with the loop-key thereof precisely in the manner in which the differentially-wound telephonewhenused is connected therewith, this coil of the converter being, 6o moreover, provided at its center with a direct ground connection.

My invention is illustrated in the accompanying drawings, in which- Figure l is a diagram illustrative of two telephone-lines-one a single or grounded line and the other'a metallic circuit line-each connected with two switchboards, together with the operators apparatus at the different boards, the operators telephone at the second 7o board being wound differentially, while at the first board the operators telephone is shown in connection with the converter. Fig. 2 is a rear elevation of my loop-key. Fig. 3 is a side elevation thereof. Fig. tis a front elevation 75 of the portion thereof below the table.

`The grounded-circuit telephone line d extends from ground at the subscribers station thereon through the switches a a2 of the different boards and thence through its indi- 8o vidual annunciator d3 to ground. The test portions of the switches a 0.2 are vconnected by the test-wire a4, this test-wire a4 being provided with a connection through high resistance to ground in the ordinary manner. The S5 metalliccircuit telephone-line b extends through the switches b b2 on the different boards and through its individual annunciator b3 on the last board, and thence to the testpiece of switch b2 and to the test-piece of 9o switch b', and thence back to the subscribers station.

At each of the switchboards I have provided a set of loop plugs and cords, an ordinary generator loop-key being connected in the circuit of the strands of each cord. 'Alistening-in key or loop-key for bridging the telephone into circuit is provided, also, in connection with each pair of plugs and cords. Thus at board 2 we have the plugs c c and Ioo their flexible cords. The ringing-key d is ineluded in the strands of cord c and the .ring-v ing-key d in the strands of cord c' in the usual manner.

I will now describe the loop-key e with reference to Figsf2, 3, and 4, in which said loopkey is shown in detail, it being understood that several such keys will be mounted upon the same support of insulating material and three metallic strips e c2 e3 provided thereon, as shown. The spring fis connected with the strand leading to the tip of one of the plugs, as plug c, while the sprin g f is connected with the strand leading to the tip of Vthe other plug, as plug c. rlhe spring f2 is connected with the wire leading to the test-battery. The spring f8 is connected by a wire with the springf and is placed in front of the spring f. When the wedge or plunger is down, as shown most clearly in Fig. 3, the spring f is closed upon the spring]08 to make electrical contact therewith.

One side of the operators telephone is connected with the strip e2 and the other side with the strip e3,while the branch from the telephone through the condenser is connected with the contact e-that is to say, the strips e2 e are connected with one side of the telephone and the strip e3 with the other side thereof, the branch which connects with contact e', however, containing the condenser. The plunger of this key is worked by a camleverin the usual way, a spring being provided for raising the plunger when the pressure from the cam-lever is taken oli. Thus by throwing down the cam-lever the spring f will be closed upon strip e and separated from springf3,while springf will close upon strip e2 and spring f2 upon strip e3.

The operators telephone g, as shown at board 2, is wound dierentially, the center of the differentialcoilsbeingconnected to ground by the branch g. The secondary of the transmitter-inductorium g2is also wound differentially, the wire g8 from one side of these differential windings extending through the condenser g4 to the strip e of the loop-key. The branch g5 from wire g3 is designed to preserve the continuity of the test-circuit when the plug c is used in making a test and to preserve the circuit between two subscribers when the operatorlistensin and is connected with the contact or strip e2 of the key. 'lhus when the operators telephone is not in circuit the circuit between the tips of the plugs is as follows: From tip of plug c', through the contacts of key d to sprin g f3, thence to spring f, thence through the contacts of key dto tip of plug c. When the operators telephone gis brought into circuit by raising the plunger of key e, the circuit is from tip of plugc tospring f', thence through contact ewire g5, condenser g4, through contact e and springf, thence to tip of plug c. When the plug c is used in testing, the test-circuit is completed, as before, through wire g5 to wire g3, thence through one dilerential coil of the coils g2 through one coil of telephone g, wire g', to earth. The wire g6 from the other side of the diiferential coils of the inductorium is connected with the strip e3 of the loop-key. When the cam-lever of key e is thrown down, the plunger will be raised and the telephone will be bridged into circuit, the test-battery will be prevented from finding circuit through the cord of the plug c', which connects with the tip thereof, so that plug c may be used as a test-plug, and when thus used if the tip is applied to the test-piece of a busy line-that is, if the tip is connected with a source of electricitythe current will find circuit through the tip of plug c', through the cord connected with the tip thereof to the spring j' of switch e, and thence by wire or branch g5 to wire g3, and thence through one of the coils of the inductorium g2 and one of the coils of the telephone g to ground through branch g. The plugs h It', their cords, the ringing-keys it', and the listening-in key k are the same in all respects as the corresponding devices shown at board 2 and hereinbefore particularly described. l

The converter Z has one of its coilsincluded in the circuit of the telephone m. The other coil thereof is provided with a branch m to ground from the central point thereof. This coil m2 of the converter is connected on one side by wire 'm3 through a condenser m4 to contact or strip e of the loop-key, a branch m5 from Wire m3 leading to the strip e2 of the switch. The other side of this coil 'm2 is connected by wire 'm6 with strip e3 of the loopswitch, these connections, it will be seen,cor responding in all respects with the connections gs, g5, and g6 at board 2. One plug h is used for testing, and when applied to the testpiece of a busy line the circuit will be completed through branch m5, one-half of the winding fm2 of the converter,and the wire m to ground. Thus the closing of the battery over the circuit thus formed will cause the usual click in the telephone m and notify the operator that the line tested is busy.

I have not deemed it necessary to describe in detail all the steps in making the connections and disconnections between the lines upon the switchboards. These connections and disconnections may be made in the ordinary manner, as is well understood.

Having thus described my invention, I claim as new and desire to secure by Letters Patent- 1. The coil of a telephone apparatus, connected between the strands of a flexible cord, and a branch connection to ground at the center of said coil, in combination with a metallic circuit including the strands of said cord in different sides thereof, substantially as and for the purpose specitied.

2. A pair of loop-plugs and their cords for connecting together and testing telephonelines, the strands of said cords including a loop-key, said loop key having contacts with different sides of the coil of a telephonic apparatus, said coil being provided with aground connection at its center, substantially as and 5 for the purpose specied.

3. The combination of a pair of loop-plugs and their cords for connecting together and testing telephone-lines and a switching device connecting with the strands of said cords,

ro said switching device having contacts with different sides of the coils of a telephonie apparatus, said coil being provided with a ground connection atits center,substantia1ly as and for vthe purpose specified.

In witness whereof I hereunto subscribe r 5 my name this 5th day of October, A. D. 1889.

JOHN J. CARTY. Witnesses:

C. G. HAWLEY, ELLA EDLER. 

